Mining Retrospective Data for Virtual Prospective Drug Repurposing: L-DOPA and Age-related Macular Degeneration

Levodopa is associated with reduced development of new-onset geographic atrophy in patients with age-related macular degeneration

BACKGROUND

Geographic atrophy (GA) is a significant cause of vision loss in patients with age-related macular degeneration (AMD). Current treatments are limited to anti-complement drugs, which have limited efficacy to delay progression with significant risk of complications. Levodopa (L-DOPA) is a byproduct of melanin synthesis that is associated with reduced development of neovascular AMD. In this study, we determined if L-DOPA was associated with a reduced likelihood of new-onset GA.

METHODS

We performed a retrospective analysis in the Vestrum Health Retina Database. We included eyes with non-neovascular AMD without GA and 1-5 years of follow-up. Eyes were divided into two groups. Exposed to L-DOPA before or on the date of non-neovascular AMD without GA diagnosis, and eyes not exposed to L-DOPA. We extracted age, sex, AREDS2 status, dry AMD stage, smoking history, and conversion rate to GA at years 1 through 5. Propensity score matching was used to match L-DOPA and control groups. Cox proportional hazard regression, adjusting for age, sex, AMD severity, AREDS2 use, smoking status, and L-DOPA use was employed to calculate hazard ratios for new-onset GA detection.

RESULTS

We identified 112,089 control and 844 L-DOPA exposed eyes with non-neovascular AMD without GA. After propensity score matching, 2532 control and 844 L-DOPA exposed eyes remained that were well-matched for age, sex, AMD severity, AREDS2 use, and smoking status. We found that L-DOPA exposure was associated with a significantly reduced likelihood (HR = 0.68, 95% CI: 0.48-0.95, P = 0.025) of new-onset GA detection.

CONCLUSION

L-DOPA use was associated with reduced detection of new-onset GA.

Retinal Function in Young Adults Following Topical Application of Levodopa to the Eye

Purpose

Levodopa has been investigated as a therapeutic solution for ocular disorders involving dysregulation of the dopaminergic system, especially in the context of myopia. However, given the critical role dopamine plays in normal vision, this phase I trial examined whether levodopa/carbidopa eye drops induce any regional changes in retinal structure and function.

Methods

Twenty-nine healthy male subjects 18 to 30 years of age were randomly assigned to receive either a low (1.4/0.34 µmoles/day, n = 14) or high (2.7/0.68 µmoles/day, n = 15) dose of levodopa/carbidopa eye drops in 1 eye for 28 consecutive days. A placebo solution was applied to all fellow eyes. Measures included visual acuity, regional frequency doubling perimetry, regional multifocal electroretinogram (mfERG) and optical coherence tomography (retinal thickness). Outcome measures were undertaken at baseline, end-of-treatment (4 weeks), and at a follow-up (4 months post-treatment).

Results

For low dose treated eyes, regional analysis showed a small, statistically significant change in mfERG recordings (increase in ring 5 amplitude in low dose treated eyes, P < 0.05) and the retinal thickness map (localized retinal thinning in low dose treated eyes, P < 0.05). These changes were not clinically significant. No significant changes were observed in high dose treated eyes. Pharmacokinetic analysis (rabbits) demonstrated that levodopa was not detectable within blood and peaked within the eye at 15 to 30 minutes (and eliminated within 4 hours).

Conclusions

No clinically significant effects of levodopa/carbidopa eye drops were found with regard to normal retinal structure and function following short-term use.

Translational Relevance

This study further demonstrates the safety of topical levodopa, which may support its use in the treatment of ocular disorders in which the dopamine system is dysregulated.

DRD2 activation inhibits choroidal neovascularization in patients with Parkinson's disease and age-related macular degeneration

Neovascular age-related macular degeneration (nAMD) remains a major cause of visual impairment and puts considerable burden on patients and health care systems. l-DOPA-treated Parkinson's disease (PD) patients have been shown to be partially protected from nAMD, but the mechanism remains unknown. Using murine models that combine 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced (MPTP-induced) PD and laser-induced nAMD with standard PD treatment of l-DOPA/DOPA-decarboxylase inhibitor or specific dopamine receptor inhibitors, we here demonstrate that l-DOPA treatment-induced increase of dopamine-mediated dopamine receptor D2 (DRD2) signaling inhibits choroidal neovascularization independently of MPTP-associated nigrostriatal pathway lesion. Analyzing a retrospective cohort of more than 200,000 patients with nAMD receiving anti-VEGF treatment from the French nationwide insurance database, we show that DRD2 agonist-treated PD patients have a significantly delayed age of onset of nAMD and reduced need for anti-VEGF therapies, similar to the effects of the l-DOPA treatment. While providing a mechanistic explanation for an intriguing epidemiological observation, our findings suggest that systemic DRD2 agonists might constitute an adjuvant therapy to delay and reduce the need for anti-VEGF therapy in patients with nAMD.

Construction of a screening system for lipid-derived radical inhibitors and validation of hit compounds to target retinal and cerebrovascular diseases

Recent studies have highlighted the indispensable role of oxidized lipids in inflammatory responses, cell death, and disease pathogenesis. Consequently, inhibitors targeting oxidized lipids, particularly lipid-derived radicals critical in lipid peroxidation, which are known as radical-trapping antioxidants (RTAs), have been actively pursued. We focused our investigation on nitroxide compounds that have rapid second-order reaction rate constants for reaction with lipid-derived radicals. A novel screening system was developed by employing competitive reactions between library compounds and a newly developed profluorescence nitroxide probe with lipid-derived radicals to identify RTA compounds. A PubMed search of the top hit compounds revealed their wide application as repositioned drugs. Notably, the inhibitory efficacy of methyldopa, selected from these compounds, against retinal damage and bilateral common carotid artery stenosis was confirmed in animal models. These findings underscore the efficacy of our screening system and suggest that it is an effective approach for the discovery of RTA compounds.

Immunogenetic and Environmental Factors in Age-Related Macular Disease

Age-related macular degeneration (AMD) is a chronic disease, which often develops in older people, but this is not the rule. AMD pathogenesis changes include the anatomical and functional complex. As a result of damage, it occurs, in the retina and macula, among other areas. These changes may lead to partial or total loss of vision. This disease can occur in two clinical forms, i.e., dry (progression is slowly and gradually) and exudative (wet, progression is acute and severe), which usually started as dry form. A coexistence of both forms is possible. AMD etiology is not fully understood. Extensive genetic studies have shown that this disease is multifactorial and that genetic determinants, along with environmental and metabolic-functional factors, are important risk factors. This article reviews the impact of heavy metals, macro- and microelements, and genetic factors on the development of AMD. We present the current state of knowledge about the influence of environmental factors and genetic determinants on the progression of AMD in the confrontation with our own research conducted on the Polish population from Kuyavian-Pomeranian and Lubusz Regions. Our research is concentrated on showing how polluted environments of large agglomerations affects the development of AMD. In addition to confirming heavy metal accumulation, the growth of risk of acute phase factors and polymorphism in the genetic material in AMD development, it will also help in the detection of new markers of this disease. This will lead to a better understanding of the etiology of AMD and will help to establish prevention and early treatment.

Repurposing of biologics and biopharmaceuticals

The field of drug repurposing is gaining attention as a way to introduce pharmaceutical agents with established safety profiles to new patient populations. This approach involves finding new applications for existing drugs through observations or deliberate efforts to understand their mechanisms of action. Recent advancements in bioinformatics and pharmacology, along with the availability of extensive data repositories and analytical techniques, have fueled the demand for novel methodologies in pharmaceutical research and development. To facilitate systematic drug repurposing, various computational methodologies have emerged, combining experimental techniques and in silico approaches. These methods have revolutionized the field of drug discovery by enabling the efficient repurposing of screens. However, establishing an ideal drug repurposing pipeline requires the integration of molecular data accessibility, analytical proficiency, experimental design expertise, and a comprehensive understanding of clinical development processes. This chapter explores the key methodologies used in systematic drug repurposing and discusses the stakeholders involved in this field. It emphasizes the importance of strategic alliances to enhance the success of repurposing existing compounds for new indications. Additionally, the chapter highlights the current benefits, considerations, and challenges faced in the repurposing process, which is pursued by both biotechnology and pharmaceutical companies. Overall, drug repurposing holds great promise in expanding the use of existing drugs and bringing them to new patient populations. With the advancements in computational methodologies and the collaboration of various stakeholders, this approach has the potential to accelerate drug development and improve patient outcomes.

Association of lipid-lowering drugs and antidiabetic drugs with age-related macular degeneration: a meta-analysis in Europeans

BACKGROUND/AIMS

To investigate the association of commonly used systemic medications with prevalent age-related macular degeneration (AMD) in the general population.

METHODS

We included 38 694 adults from 14 population-based and hospital-based studies from the European Eye Epidemiology consortium. We examined associations between the use of systemic medications and any prevalent AMD as well as any late AMD using multivariable logistic regression modelling per study and pooled results using random effects meta-analysis.

RESULTS

Between studies, mean age ranged from 61.5±7.1 to 82.6±3.8 years and prevalence ranged from 12.1% to 64.5% and from 0.5% to 35.5% for any and late AMD, respectively. In the meta-analysis of fully adjusted multivariable models, lipid-lowering drugs (LLD) and antidiabetic drugs were associated with lower prevalent any AMD (OR 0.85, 95% CI=0.79 to 0.91 and OR 0.78, 95% CI=0.66 to 0.91). We found no association with late AMD or with any other medication.

CONCLUSION

Our study indicates a potential beneficial effect of LLD and antidiabetic drug use on prevalence of AMD across multiple European cohorts. Our findings support the importance of metabolic processes in the multifactorial aetiology of AMD.

Repurposing Drugs: An Empowering Approach to Drug Discovery and Development

Drug discovery and development is a time-consuming and costly procedure that necessitates a substantial effort. Drug repurposing has been suggested as a method for developing medicines that takes less time than developing brand new medications and will be less expensive. Also known as drug repositioning or re-profiling, this strategy has been in use from the time of serendipitous drug discoveries to the modern computer aided drug designing and use of computational chemistry. In the light of the COVID-19 pandemic too, drug repurposing emerged as a ray of hope in the dearth of available medicines. Data availability by electronic recording, libraries, and improvements in computational techniques offer a vital substrate for systemic evaluation of repurposing candidates. In the not-too-distant future, it could be possible to create a global research archive for us to access, thus accelerating the process of drug development and repurposing. This review aims to present the evolution, benefits and drawbacks including current approaches, key players and the legal and regulatory hurdles in the field of drug repurposing. The vast quantities of available data secured in multiple drug databases, assisting in drug repurposing is also discussed.

Small-Molecule Drug Repurposing for Counteracting Phototoxic A2E Aggregation

Despite the well-established role of oxidative stress in the pathogenesis of age-related macular degeneration (AMD), the mechanism underlying phototoxicity remains unclear. Herein, we used a drug repurposing approach to isolate an FDA-approved drug that blocks the aggregation of the photoinducible major fluorophore of lipofuscin, the bis-retinoid N-retinylidene-N-retinylethanolamine (A2E). Our fluorescence-based screening combined with dynamic light scattering (DLS) analysis led to the identification of entacapone as a potent inhibitor of A2E fluorescence and aggregation. The entacapone-mediated inhibition of A2E aggregation blocks its photodegradation and offers photoprotection in A2E-loaded retinal pigment epithelial (RPE) cells exposed to blue light. In-depth mechanistic analysis suggests that entacapone prevents the conversion of toxic aggregates by redirecting A2E into off-pathway oligomers. These findings provide evidence that aggregation contributes to the phototoxicity of A2E.

Levodopa Is Associated with Reduced Development of Neovascular Age-Related Macular Degeneration

OBJECTIVE

To determine whether levodopa (L-DOPA) is associated with a reduced likelihood of developing neovascular age-related macular degeneration (AMD).

DESIGN

Three studies were performed: retrospective analyses in the Vestrum Health Retina Database (#1-2) and case-control analysis in the Merative MarketScan Research Databases (#3).

PARTICIPANTS

Eyes with neovascular AMD and 2 years of follow-up (#1). Eyes with non-neovascular AMD and 1 to 5 years of follow-up (#2). Patients aged ≥ 55 years with newly diagnosed neovascular AMD matched to controls without neovascular AMD (#3).

METHODS

Eyes were divided into 2 groups (#1-2): exposed to L-DOPA before or on the date of neovascular (#1) or nonneovascular (#2) AMD diagnosis, and eyes not exposed to L-DOPA. We extracted AMD risk factors, number of intravitreal injections (#1), and conversion rate to neovascular AMD (#2). We calculated the percentage of newly diagnosed neovascular AMD cases and matched controls exposed to any L-DOPA and determined the cumulative 2-year dose in grams by tertiles (< 100 mg, approximately 100-300 mg, and approximately > 300 mg per day, #3).

MAIN OUTCOME MEASURES

Number of intravitreal injections (#1) and detection of new-onset neovascular AMD (#2-3) after adjusting for AMD risk factors.

RESULTS

In the Vestrum database, eyes with neovascular AMD that were exposed to L-DOPA underwent 1 fewer intravitreal injection over 2 years (N = 84 088 control vs. 530 L-DOPA eyes, P = 0.006). In eyes with nonneovascular AMD (N = 42 081-203 155 control vs. 314-1525 L-DOPA eyes), L-DOPA exposure was associated with a reduced risk of conversion to neovascular AMD by 21% at year 2 (P = 0.029), 35% at years 3 to 4 (P < 0.001), and 28% at year 5 (P = 0.024). In the MarketScan databases (N = 86 900 per group), cumulative 2-year doses of L-DOPA between approximately 100 to 300 mg per day and approximately > 300 mg were associated with decreased odds of developing neovascular AMD by 15% (odds ratio [OR], 0.85; 95% confidence interval [CI], 0.75-0.97) and 23% (OR, 0.77; 95% CI, 0.67-0.87), respectively.

CONCLUSIONS

Levodopa use was associated with reduced detection of new-onset neovascular AMD. A prospective, randomized clinical trial should be considered to investigate whether low-dose L-DOPA reduces neovascular AMD conversion.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Oxidative and Endoplasmic Reticulum Stress Represent Novel Therapeutic Targets for Choroideremia

Choroideremia (CHM) is a rare X-linked chorioretinal dystrophy, affecting the photoreceptors, retinal pigment epithelium (RPE) and choroid, with no approved therapy. CHM is caused by mutations in the CHM gene, which encodes the ubiquitously expressed Rab escort protein 1 (REP1). REP1 is involved in prenylation, a post-translational modification of Rab proteins, and plays an essential role in intracellular trafficking. In this study, we examined oxidative and endoplasmic reticulum (ER) stress pathways in chmru848 zebrafish and CHMY42X patient fibroblasts, and screened a number of neuroprotectants for their ability to reduce stress. The expression of the oxidative stress markers txn, cat and sod3a, and the ER stress markers bip, atf4 and atf6, were dysregulated in chmru848 fish. The expression of SOD2 was also reduced in CHMY42X fibroblasts, along with reduced BIP and increased CHOP expression. The lack of REP1 is associated with defects in vesicular trafficking, photoreceptor outer segment phagocytosis and melanosome transport, leading to increased levels of stress within the retina and RPE. Drugs targeting oxidative and ER stress pathways represent novel therapeutic avenues.

Repurposing medications for treatment of age-related macular degeneration: Insights from novel approaches to data mining

The economic and visual burdens associated with age-related macular degeneration (AMD) are expected to significantly increase in the coming years. As of now, interventions to delay or prevent AMD are limited. Hence, there is an urgent and unmet need to expand our therapeutic tools for AMD in a manner, that is, both efficient and cost-effective. In this review, we consider the idea of drug repurposing, in which existing medications with other indications can be re-imagined for treating AMD. We detail the results of several population-level studies that have shown associations between several candidates and decreased risk of AMD development or progression. Such candidates include the more extensively studied metformin and statins, in addition to recently identified candidates fluoxetine and l-DOPA (levodopa) that show promise. We then briefly explore results from an advanced bioinformatics study, which provides further evidence that existing medications are associated with AMD risk genes. Many of these candidates warrant further study in prospective, clinical trials, where their potential causal relationships with AMD can be thoroughly assessed.

Mechanism of circular RNA-mediated regulation of L-DOPA to improve wet age-related macular degeneration

This study aimed to investigate the effect and mechanism of levodopa (L-DOPA) in the treatment of age-related macular degeneration (AMD). A wet AMD cell model was created via CoCl₂ treatment of ARPE-19 cells. The cytoprotective effects of L-DOPA in the model were determined using CCK-8, flow cytometry, TUNEL, qPCR, and ELISA assays. Subsequently, circRNA sequencing and bioinformatics analysis were used to screen differentially expressed circRNAs, which were overexpressed in ARPE-19 cells, to explore their role in wet AMD. The findings revealed that 200 μM CoCl₂ treatment inhibited the cell viability and the production of tyrosinase, melanin, and pigment epithelium-derived growth factor but promoted apoptosis and the expression of vascular endothelial growth factor in ARPE-19 cells. Moreover, 20 μM L-DOPA exerted the best therapeutic effect on the model. qPCR showed that Hsa_circ_0018401 (circ-SGMS1) was significantly differentially expressed in each experimental group, which was consistent with the sequencing results. The overexpression of circ-SGMS1 in ARPE-19 cells reversed the effects of CoCl₂. Fluorescence in situ hybridization showed that circ-SGMS1 was expressed more in the nucleus than in the cytoplasm. qPCR assays indicated that circ-SGMS1 overexpression did not have a significant effect on the expressions of VEGFA and KDR but significantly reduced the expressions of HIF-1a and THBS1. Circ-SGMS1 is of immense significance in the AMD treatment mechanism of L-DOPA. Overexpression of circ-SGMS1 may alleviate wet AMD by inhibiting HIF-1a and THBS1 expression.

Diabetic rats with high levels of endogenous dopamine do not show retinal vascular pathology

Purpose

Limited research exists on the time course of long-term retinal and cerebral deficits in diabetic rodents. Previously, we examined short term (4-8 weeks) deficits in the Goto-Kakizaki (GK) rat model of Type II diabetes. Here, we investigated the long-term (1-8 months) temporal appearance of functional deficits (retinal, cognitive, and motor), retinal vascular pathology, and retinal dopamine levels in the GK rat.

Methods

In GK rats and Wistar controls, retinal neuronal function (electroretinogram), cognitive function (Y-maze), and motor function (rotarod) were measured at 1, 2, 4, 6, and 8 months of age. In addition, we evaluated retinal vascular function (functional hyperemia) and glucose and insulin tolerance. Retinas from rats euthanized at ≥8 months were assessed for vascular pathology. Dopamine and DOPAC levels were measured via HPLC in retinas from rats euthanized at 1, 2, 8, and 12 months.

Results

Goto-Kakizaki rats exhibited significant glucose intolerance beginning at 4 weeks and worsening over time (p < 0.001). GK rats also showed significant delays in flicker and oscillatory potential implicit times (p < 0.05 to p < 0.001) beginning at 1 month. Cognitive deficits were observed beginning at 6 months (p < 0.05), but no motor deficits. GK rats showed no deficits in functional hyperemia and no increase in acellular retinal capillaries. Dopamine levels were twice as high in GK vs. Wistar retinas at 1, 2, 8, and 12 months (p < 0.001).

Conclusion

As shown previously, retinal deficits were detectable prior to cognitive deficits in GK rats. While retinal neuronal function was compromised, retinal vascular pathology was not observed, even at 12+ months. High endogenous levels of dopamine in the GK rat may be acting as an anti-angiogenic and providing protection against vascular pathology.

Effects of systemic drugs on the development and progression of age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of severe loss of central vision among people over 50. The pathophysiology of the disease is multifactorial and can be attributed to genetics, aging, inflammation, environmental factors, and lifestyle factors including smoking, diet, obesity, and alcohol consumption. While there is no treatment for dry AMD, the current standard treatment for wet AMD is an intraocular injection of anti-vascular endothelial growth factor-an effective, yet expensive, therapy that requires ongoing treatment. As the aging population continues to grow, and AMD diagnoses continue to rise, new treatments should be explored to reduce vision complications and decrease treatment burdens. Many systemic conditions have progressive pathological changes that may affect AMD, particularly those affecting systemic vasculature like diabetes and cardiovascular status. Consequently, systemic drugs used to treat coexistent systemic diseases may influence some of the pathogenic mechanisms of AMD and lead its progression or delay. In this review we explore the current literature to summarize the findings of the reported effects of antihypertensive, immunosuppressants, cholesterol lowering agents, nonsteroidal anti-inflammatory drugs, dopamine precursors, hypoglycemic agents, and anticoagulants on AMD.

Repurposing Drugs for Treatment of Age-Related Macular Degeneration

The need for new drugs to treat dry forms of age-related macular degeneration remains high. A promising approach is repurposing of FDA-approved medications to treat AMD. Databases containing medical and drug records allow for retroactive identification of drugs whose use correlates with reduced AMD diagnosis. This short review summarizes progress in several classes of drugs considered for repurposing: GPR-143 agonists (L-DOPA), anti-diabetic drugs (metformin, acarbose, empagliflozin, fenofibrate), mitochondrial activators (PU-91), and serotonin pathway drugs (fluoxetine, flibanserin, xaliproden, buspirone). The promises and caveats of repurposing are discussed herein.

Decoding Race and Age-Related Macular Degeneration: GPR 143 Activity Is the Key

Age-related macular degeneration (AMD) is a leading cause of irreversible blindness in the developed world. Caucasians are eightfold more likely to develop AMD than any other race, indicating a racial bias in AMD incidence which is unexplained. We hypothesize that pigmentation of the retinal pigment epithelium (RPE) and choroid protects from AMD and underlies this peculiar racial bias. We investigated GPR143, a receptor in the pigmentation pathway, which is activated by a melanin synthesis by-product, l-dopa. In this model, greater pigmentation leads to greater l-dopa production and, in turn, greater GPR143 signaling. GPR143 activity upregulates PEDF and downregulates both VEGF and exosomes; all of which reduce the angiogenic potential in the retina. Moreover, we demonstrate that GPR143 signaling enhances the digestion of shed photoreceptor outer segments. Together, our data suggests a central role for GPR143 signaling in RPE-photoreceptor interaction which is critical to healthy vision.

Current perspective on retinal remodeling: Implications for therapeutics

The retinal degenerative diseases retinitis pigmentosa and age-related macular degeneration are a leading cause of irreversible vision loss. Both present with progressive photoreceptor degeneration that is further complicated by processes of retinal remodeling. In this perspective, we discuss the current state of the field of retinal remodeling and its implications for vision-restoring therapeutics currently in development. Here, we discuss the challenges and pitfalls retinal remodeling poses for each therapeutic strategy under the premise that understanding the features of retinal remodeling in totality will provide a basic framework with which therapeutics can interface. Additionally, we discuss the potential for approaching therapeutics using a combined strategy of using diffusible molecules in tandem with other vision-restoring therapeutics. We end by discussing the potential of the retina and retinal remodeling as a model system for more broadly understanding the progression of neurodegeneration across the central nervous system.

Potential therapeutic strategies for photoreceptor degeneration: the path to restore vision

Photoreceptors (PRs), as the most abundant and light-sensing cells of the neuroretina, are responsible for converting light into electrical signals that can be interpreted by the brain. PR degeneration, including morphological and functional impairment of these cells, causes significant diminution of the retina's ability to detect light, with consequent loss of vision. Recent findings in ocular regenerative medicine have opened promising avenues to apply neuroprotective therapy, gene therapy, cell replacement therapy, and visual prostheses to the challenge of restoring vision. However, successful visual restoration in the clinical setting requires application of these therapeutic approaches at the appropriate stage of the retinal degeneration. In this review, firstly, we discuss the mechanisms of PR degeneration by focusing on the molecular mechanisms underlying cell death. Subsequently, innovations, recent developments, and promising treatments based on the stage of disorder progression are further explored. Then, the challenges to be addressed before implementation of these therapies in clinical practice are considered. Finally, potential solutions to overcome the current limitations of this growing research area are suggested. Overall, the majority of current treatment modalities are still at an early stage of development and require extensive additional studies, both pre-clinical and clinical, before full restoration of visual function in PR degeneration diseases can be realized.

The safety and tolerability of levodopa eye drops for the treatment of ocular disorders: A randomized first-in-human study

Myopia is the leading cause of low vision worldwide and can lead to significant pathological complications. Therefore, to improve patient outcomes, the field continues to develop novel interventions for this visual disorder. Accordingly, this first-in-human study reports on the safety profile of a novel dopamine-based ophthalmic treatment for myopia, levodopa/carbidopa eye drops. This phase I, first-in-human, monocenter, placebo-controlled, double-blind, paired-eye, multidose, randomized clinical trial was undertaken in healthy adult males aged 18-30 years (mean age 24.9 ± 2.7) at the University of Canberra Eye Clinic, Australia. Participants were randomly assigned to receive either a low (1.4 levodopa:0.34 carbidopa [μmoles/day], n = 14) or standard dose (2.7 levodopa:0.68 carbidopa [μmoles/day], n = 15) of levodopa/carbidopa eye drops in one eye and placebo in the fellow eye once daily for 4 weeks (28 days). Over this 4-week trial, and after a 4-month follow-up visit, levodopa/carbidopa treatment had no significant effect on ocular tolerability and anterior surface integrity, visual function, ocular health, refraction/ocular biometry, and did not induce any non-ocular adverse events. These results indicate that topical levodopa/carbidopa is safe and tolerable to the eye, paving the way for future studies on the efficacy of this novel ophthalmic formulation in the treatment of human myopia. The findings of this study have implications not only for the treatment of myopia, but in a number of other visual disorders (i.e., amblyopia, diabetic retinopathy, and age-related macular degeneration) in which levodopa has been identified as a potential clinical intervention.

The retinal pigmentation pathway in human albinism: Not so black and white

Albinism is a pigment disorder affecting eye, skin and/or hair. Patients usually have decreased melanin in affected tissues and suffer from severe visual abnormalities, including foveal hypoplasia and chiasmal misrouting. Combining our data with those of the literature, we propose a single functional genetic retinal signalling pathway that includes all 22 currently known human albinism disease genes. We hypothesise that defects affecting the genesis or function of different intra-cellular organelles, including melanosomes, cause syndromic forms of albinism (Hermansky-Pudlak (HPS) and Chediak-Higashi syndrome (CHS)). We put forward that specific melanosome impairments cause different forms of oculocutaneous albinism (OCA1-8). Further, we incorporate GPR143 that has been implicated in ocular albinism (OA1), characterised by a phenotype limited to the eye. Finally, we include the SLC38A8-associated disorder FHONDA that causes an even more restricted "albinism-related" ocular phenotype with foveal hypoplasia and chiasmal misrouting but without pigmentation defects. We propose the following retinal pigmentation pathway, with increasingly specific genetic and cellular defects causing an increasingly specific ocular phenotype: (HPS1-11/CHS: syndromic forms of albinism)-(OCA1-8: OCA)-(GPR143: OA1)-(SLC38A8: FHONDA). Beyond disease genes involvement, we also evaluate a range of (candidate) regulatory and signalling mechanisms affecting the activity of the pathway in retinal development, retinal pigmentation and albinism. We further suggest that the proposed pigmentation pathway is also involved in other retinal disorders, such as age-related macular degeneration. The hypotheses put forward in this report provide a framework for further systematic studies in albinism and melanin pigmentation disorders.

Therapeutic Approaches for Age-Related Macular Degeneration

Damage to the retinal pigment epithelium, Bruch's membrane and/or tissues underlying macula is known to increase the risk of age-related macular degeneration (AMD). AMD is commonly categorized in two distinct types, namely, the nonexudative (dry form) and the exudative (wet form). Currently, there is no ideal treatment available for AMD. Recommended standard treatments are based on the use of vascular endothelial growth factor (VEGF), with the disadvantage of requiring repeated intravitreal injections which hinder patient's compliance to the therapy. In recent years, several synthetic and natural active compounds have been proposed as innovative therapeutic strategies against this disease. There is a growing interest in the development of formulations based on nanotechnology because of its important role in the management of posterior eye segment disorders, without the use of intravitreal injections, and furthermore, with the potential to prolong drug release and thus reduce adverse effects. In the same way, 3D bioprinting constitutes an alternative to regeneration therapies for the human retina to restore its functions. The application of 3D bioprinting may change the current and future perspectives of the treatment of patients with AMD, especially those who do not respond to conventional treatment. To monitor the progress of AMD treatment and disease, retinal images are used. In this work, we revised the recent challenges encountered in the treatment of different forms of AMD, innovative nanoformulations, 3D bioprinting, and techniques to monitor the progress.

Applications of natural language processing in ophthalmology: present and future

Advances in technology, including novel ophthalmic imaging devices and adoption of the electronic health record (EHR), have resulted in significantly increased data available for both clinical use and research in ophthalmology. While artificial intelligence (AI) algorithms have the potential to utilize these data to transform clinical care, current applications of AI in ophthalmology have focused mostly on image-based deep learning. Unstructured free-text in the EHR represents a tremendous amount of underutilized data in big data analyses and predictive AI. Natural language processing (NLP) is a type of AI involved in processing human language that can be used to develop automated algorithms using these vast quantities of available text data. The purpose of this review was to introduce ophthalmologists to NLP by (1) reviewing current applications of NLP in ophthalmology and (2) exploring potential applications of NLP. We reviewed current literature published in Pubmed and Google Scholar for articles related to NLP and ophthalmology, and used ancestor search to expand our references. Overall, we found 19 published studies of NLP in ophthalmology. The majority of these publications (16) focused on extracting specific text such as visual acuity from free-text notes for the purposes of quantitative analysis. Other applications included: domain embedding, predictive modeling, and topic modeling. Future ophthalmic applications of NLP may also focus on developing search engines for data within free-text notes, cleaning notes, automated question-answering, and translating ophthalmology notes for other specialties or for patients, especially with a growing interest in open notes. As medicine becomes more data-oriented, NLP offers increasing opportunities to augment our ability to harness free-text data and drive innovations in healthcare delivery and treatment of ophthalmic conditions.

The Many Faces of G Protein-Coupled Receptor 143, an Atypical Intracellular Receptor

GPCRs transform extracellular stimuli into a physiological response by activating an intracellular signaling cascade initiated via binding to G proteins. Orphan G protein-coupled receptors (GPCRs) hold the potential to pave the way for development of new, innovative therapeutic strategies. In this review we will introduce G protein-coupled receptor 143 (GPR143), an enigmatic receptor in terms of classification within the GPCR superfamily and localization. GPR143 has not been assigned to any of the GPCR families due to the lack of common structural motifs. Hence we will describe the most important motifs of classes A and B and compare them to the protein sequence of GPR143. While a precise function for the receptor has yet to be determined, the protein is expressed abundantly in pigment producing cells. Many GPR143 mutations cause X-linked Ocular Albinism Type 1 (OA1, Nettleship-Falls OA), which results in hypopigmentation of the eyes and loss of visual acuity due to disrupted visual system development and function. In pigment cells of the skin, loss of functional GPR143 results in abnormally large melanosomes (organelles in which pigment is produced). Studies have shown that the receptor is localized internally, including at the melanosomal membrane, where it may function to regulate melanosome size and/or facilitate protein trafficking to the melanosome through the endolysosomal system. Numerous additional roles have been proposed for GPR143 in determining cancer predisposition, regulation of blood pressure, development of macular degeneration and signaling in the brain, which we will briefly describe as well as potential ligands that have been identified. Furthermore, GPR143 is a promiscuous receptor that has been shown to interact with multiple other melanosomal proteins and GPCRs, which strongly suggests that this orphan receptor is likely involved in many different physiological actions.

The Inhibitory Effect of Selected D2 Dopaminergic Receptor Agonists on VEGF-Dependent Neovascularization in Zebrafish Larvae: Potential New Therapy in Ophthalmic Diseases

Pathological angiogenesis is correlated with many ophthalmic diseases. The most common are exudative age-related macular degeneration and proliferative diabetic retinopathy. The current treatment for these diseases is based on regularly administered anti-VEGF antibodies injections. In the study, we investigated selected D₂ dopaminergic receptor agonists, namely bromocriptine, cabergoline and pergolide, on hypoxia-induced neovascularization. We used the zebrafish laboratory model, specifically three-day post fertilization (dpf) Tg(fli-1: EGFP) zebrafish larvae. To induce abnormal angiogenesis of hyaloid-retinal vessels (HRVs) and intersegmental vessels (ISVs), the larvae were treated with cobalt chloride (II) (CoCl₂) (a hypoxia-inducing agent) from 24 h post fertilization. The inhibitory role of D₂ dopaminergic receptor agonists was investigated using confocal microscopy and qPCR. Additionally, the results were compared to those obtained in the group treated with CoCl₂ followed by bevacizumab, the well-known antiangiogenic agent. Confocal microscopy analyses revealed severe deformation of vessels in the CoCl₂ treated group, while co-incubation with bromocriptine, cabergoline, pergolide and bevacizumab, respectively, significantly inhibited abnormalities of angiogenesis. The qPCR analyses supported the protective role of the chosen dopaminergic agonists by demonstrating their influence on CoCl₂-derived upregulation of vegfaa expression. The present results suggest that the D₂ receptor agonists can be considered as a new direction in research for antiangiogenic therapy.

Patients with Obesity and a History of Metformin Treatment Have Lower Influenza Mortality: A Retrospective Cohort Study

Background: Obesity is a risk factor for the development of influenza by leading to a chronic inflammatory state and T-cell dysfunction. Based upon preclinical research, metformin has influenza activity by restoring T-cell function and improving the immune response. Objective: We aimed to evaluate the potential drug repurposing of metformin for the management of influenza among patients with obesity utilizing national claims data in an electronic health record database. Methods: The VA Informatics and Computing Infrastructure (VINCI) was utilized to obtain individual-level information on demographics, administrative claims, and pharmacy dispensation. A cohort was created among individuals with laboratory confirmed diagnosis of influenza with a diagnosis of fever, cough, influenza, or acute upper respiratory infection in an outpatient setting. The study outcome was death after diagnosis of influenza. Cohorts were formed using diabetes status and metformin exposure prior to a positive influenza diagnosis. Hazard ratios for mortality were estimated using a cox proportional hazards model adjusting for baseline covariates and a sub-analysis was conducted utilizing propensity score matching. A greedy nearest neighbor algorithm was utilized to match 1 to 1 non-metformin diabetic controls and non-diabetic controls to diabetic patients receiving metformin. Results: A total of 3551 patients met the inclusion criteria and were evaluated in our study. The cohorts consisted of 1461 patients in the non-diabetic cohort, 1597 patients in the diabetic / metformin cohort, and 493 patients in the diabetic no metformin cohort. Compared to non-diabetic patients, diabetic patients with metformin had a lower rate of death (aHR 0.78, 95% CI 0.609–0.999). There was not a statistical difference between the non-diabetic patients and the diabetic patients without metformin (aHR 1.046, 95% CI 0.781–1.400). The propensity score matched cohorts revealed consistent results with the primary analysis. Conclusion: Our results demonstrated patients with obesity and a history of metformin treatment have lower influenza mortality.

Depletion of Retinal Dopaminergic Activity in a Mouse Model of Rod Dysfunction Exacerbates Experimental Autoimmune Uveoretinitis: A Role for the Gateway Reflex

The gateway reflex is a mechanism by which neural inputs regulate chemokine expression at endothelial cell barriers, thereby establishing gateways for the invasion of autoreactive T cells into barrier-protected tissues. In this study, we hypothesized that rod photoreceptor dysfunction causes remodeling of retinal neural activity, which influences the blood–retinal barrier and the development of retinal inflammation. We evaluated this hypothesis using Gnat1^rd17 mice, a model of night blindness with late-onset rod-cone dystrophy, and experimental autoimmune uveoretinitis (EAU). Retinal remodeling and its effect on EAU development were investigated by transcriptome profiling, target identification, and functional validation. We showed that Gnat1^rd17 mice primarily underwent alterations in their retinal dopaminergic system, triggering the development of an exacerbated EAU, which was counteracted by dopamine replacement with L-DOPA administered either systemically or locally. Remarkably, dopamine acted on retinal endothelial cells to inhibit NF-κB and STAT3 activity and the expression of downstream target genes such as chemokines involved in T cell recruitment. These results suggest that rod-mediated dopamine release functions in a gateway reflex manner in the homeostatic control of immune cell entry into the retina, and the loss of retinal dopaminergic activity in conditions associated with rod dysfunction increases the susceptibility to autoimmune uveitis.

The use of real-world data in drug repurposing

Drug repurposing, or repositioning, is to identify new uses for existing drugs. Significantly reducing the costs and time-to-market of a medication, drug repurposing has been an alternative tool to accelerate drug development process. On the other hand, 'real world data (RWD)' has been also increasingly used to support drug development process owing to its better representing actual pattern of drug treatment and outcome in real world. In the healthcare domain, RWD refers to data collected from sources other than traditional clinical trials; for example, in electronic health records or claims and billing data. With the enactment of the 21st Century Cures Act, which encourages the use of RWD in drug development and repurposing as well, such increasing trend in RWD use will be expedited. In this context, this review provides an overview of recent progresses in the area of drug repurposing where RWD was used by firstly introducing the increasing trend and regulatory change in the use of RWD in drug development, secondly reviewing published works using RWD in drug repurposing, classifying them in the repurposing strategy, and lastly addressing limitations and advantages of RWDs.

Drug repurposing of dextromethorphan as a cellular target for the management of influenza

BACKGROUND

Influenza viruses are responsible for seasonal epidemics and sporadic pandemics of varying severity in humans, and additional treatment options are needed. High-throughput siRNA screens and a pre-clinical research model demonstrated that dextromethorphan (DM) has anti-viral activity as a cellular target for treatment of influenza. This study examined DM usage and hospitalization rates among patients with laboratory-confirmed influenza in a national cohort of United States veterans. We aimed to evaluate the potential drug repurposing of DM as a cellular target for the management of influenza utilizing a large, national claims and electronic health record database.

METHODS

This retrospective drug-disease association cohort study was conducted using data from the Veterans Affairs Informatics and Computing Infrastructure (VINCI). We used a cohort with laboratory-confirmed diagnosis of influenza and international classification of disease (ICD)-9/10 diagnosis codes of fever, cough, influenza, or acute upper respiratory infection in an outpatient setting. The study outcome is inpatient hospitalization (all-cause and respiratory) within 30 days of influenza diagnosis. We estimated the relative risk for all-cause and respiratory hospitalizations using Poisson generalized linear model (GLM) and a greedy nearest neighbor propensity score 1:1 matched sub-analysis for both hospitalization models.

FINDINGS

A total of 18,677 patients met the inclusion and exclusion criteria and were evaluated in our study. The cohorts consisted of 2801 patients dispensed DM and 15,876 untreated patients (no DM). The Poisson GLM adjusted for covariates demonstrated a relative risk reduction of 34% for all-cause hospitalizations (Relative Risk (RR) 0.66, 95% Confidence Interval (CI) 0.525-0.832) and 40% for respiratory hospitalizations (RR 0.597, 95% CI 0.423-0.843) in patients with influenza treated with DM.

CONCLUSION

Influenza viruses continue to emerge and cause infection (including pandemics) in humans, so there remains a critical need to advance the understanding of influenza treatment. Our results demonstrated reduced hospitalization rates for influenza patients treated with DM. Further research on cellular targets and/or DM is warranted for the treatment of influenza.

Emulated Clinical Trials from Longitudinal Real-World Data Efficiently Identify Candidates for Neurological Disease Modification: Examples from Parkinson's Disease

Real-world healthcare data hold the potential to identify therapeutic solutions for progressive diseases by efficiently pinpointing safe and efficacious repurposing drug candidates. This approach circumvents key early clinical development challenges, particularly relevant for neurological diseases, concordant with the vision of the 21st Century Cures Act. However, to-date, these data have been utilized mainly for confirmatory purposes rather than as drug discovery engines. Here, we demonstrate the usefulness of real-world data in identifying drug repurposing candidates for disease-modifying effects, specifically candidate marketed drugs that exhibit beneficial effects on Parkinson's disease (PD) progression. We performed an observational study in cohorts of ascertained PD patients extracted from two large medical databases, Explorys SuperMart (N = 88,867) and IBM MarketScan Research Databases (N = 106,395); and applied two conceptually different, well-established causal inference methods to estimate the effect of hundreds of drugs on delaying dementia onset as a proxy for slowing PD progression. Using this approach, we identified two drugs that manifested significant beneficial effects on PD progression in both datasets: rasagiline, narrowly indicated for PD motor symptoms; and zolpidem, a psycholeptic. Each confers its effects through distinct mechanisms, which we explored via a comparison of estimated effects within the drug classification ontology. We conclude that analysis of observational healthcare data, emulating otherwise costly, large, and lengthy clinical trials, can highlight promising repurposing candidates, to be validated in prospective registration trials, beneficial against common, late-onset progressive diseases for which disease-modifying therapeutic solutions are scarce.

Identification of a novel GPR143 mutation in a large Chinese family with isolated foveal hypoplasia

Background

Pathogenic variants of G-protein coupled receptor 143 (GPR143) gene often leads to ocular albinism type I (OA1) characterized by nystagmus, iris and fundus hypopigmentation, and foveal hypoplasia. In this study, we identified a novel hemizygous nonsense mutation in GPR143 that caused an atypical manifestation of OA1.

Case presentation

We reported a large Chinese family in which all affected individuals are afflicted with poor visual acuity and foveal hypoplasia without signs of nystagmus. Fundus examination of patients showed an absent foveal reflex and mild hypopigmentation. The fourth grade of foveal hypoplasia and the reduced area of blocked fluorescence at foveal region was detected in OCT. OCTA imaging showed the absence of foveal avascular zone. In addition, the amplitude of multifocal ERG was reduced in the central ring. Gene sequencing results revealed a novel hemizygous mutation (c.939G > A) in GPR143 gene, which triggered p.W313X. However, no iris depigmentation and nystagmus were observed among both patients and carriers.

Conclusions

In this study, we reported a novel nonsense mutation of GPR143 in a large family with poor visual acuity and isolated foveal hypoplasia without nystagmus, which further expanded the genetic mutation spectrum of GPR143.

New insights into oxidative stress and immune mechanisms involved in age-related macular degeneration tackled by novel therapies

The prevalence of age-related macular degeneration (AMD) has increased in the last years. Although anti-VEGF agents have improved the prognosis of exudative AMD, dry AMD has still devastating effects on elderly people vision. Oxidative stress and inflammation are mechanisms involved in AMD pathogenesis and its progression. Molecular pathways involving epidermal growth factor receptor (EGFR), bone morphogenetic protein (BMP4) and the nuclear erythroid related factor 2 (Nrf2) are behind oxidative stress in AMD due to their participation in antioxidant cellular pathways. As a consequence of the disbalance produced in the antioxidant mechanisms, there is an activation of innate and adaptative immune response with cell recruitment, changes in complement factors expression, and modification of cellular milieu. Different therapies are being studied to treat dry AMD based on the possible effects on antioxidant molecular pathways or their action on the immune response. There is a wide range of treatments presented in this review, from natural antioxidant compounds to cell and gene therapy, based on their mechanisms. Finally, we hypothesize that alpha-1-antitrypsin (AAT), an anti-inflammatory and immunomodulatory molecule that can also modulate antioxidant cellular defenses, could be a good candidate for testing in AMD. This article is part of the special ssue on 'The Quest for Disease-Modifying Therapies for Neurodegenerative Disorders'.

Levodopa Positively Affects Neovascular Age-Related Macular Degeneration

BACKGROUND

Age-related macular degeneration (AMD) is a common cause of blindness worldwide. Neovascular AMD (nAMD) is an advanced form of the disease, in which excess vascular endothelial growth factor (VEGF) induces growth of new blood vessels that leak fluid, accounting for 90% of vision loss in AMD. Dysfunction of the retinal pigment epithelium likely initiates AMD. Retinal pigment epithelial cells express a G protein-coupled receptor, GPR143, which downregulates VEGF in response to levodopa. Anti-VEGF therapy effectively treats nAMD, suggesting that excessive VEGF activity drives the pathology.

METHODS

In an open-label pilot study, in patients with newly diagnosed nAMD and naïve to anti-VEGF injections (Cohort-1), the effects of carbidopa-levodopa on vision and anatomic outcomes were evaluated for 4 weeks. Then patients were followed 5 months further with ascending levodopa doses. Patients previously treated with anti-VEGF injection therapy (Cohort-2) were also treated with ascending levodopa doses and evaluated for 6 months.

RESULTS

Levodopa was safe, well tolerated, and delayed anti-VEGF injection therapy while improving visual outcomes. In the first month, retinal fluid decreased by 29% (P = .02, n = 12) without anti-VEGF treatment. Through 6 months the decrease in retinal fluid was sustained, with a mean frequency of 0.38 injections/month. At month 6, mean visual acuity improved by 4.7 letters in Cohort-1 (P = .004, n = 15) and by 4.8 letters in Cohort-2 (P = .02, n = 11). Additionally, there was a 52% reduction in the need for anti-VEGF injections in Cohort-2 (P = .002).

CONCLUSIONS

Our findings suggest efficacy and support the pharmacological targeting of GPR143 with levodopa for the treatment of nAMD in future studies.

Targeting abnormal metabolism in Alzheimer's disease: The Drug Repurposing for Effective Alzheimer's Medicines (DREAM) study

Drug discovery for disease-modifying therapies for Alzheimer's disease and related dementias (ADRD) based on the traditional paradigm of experimental animal models has been disappointing. We describe the rationale and design of the Drug Repurposing for Effective Alzheimer's Medicines (DREAM) study, an innovative multidisciplinary alternative to traditional drug discovery. First, we use a systems biology perspective in the "hypothesis generation" phase to identify metabolic abnormalities that may either precede or interact with the accumulation of ADRD neuropathology, accelerating the expression of clinical symptoms of the disease. Second, in the "hypothesis refinement" phase we propose use of large patient cohorts to test whether drugs approved for other indications that also target metabolic drivers of ADRD pathogenesis might alter the trajectory of the disease. We emphasize key challenges in population-based pharmacoepidemiologic studies aimed at quantifying the association between medication use and ADRD onset and outline robust causal inference principles to safeguard against common pitfalls. Candidate ADRD treatments emerging from this approach will hold promise as plausible disease-modifying therapies for evaluation in randomized controlled trials.

Harnessing endophenotypes and network medicine for Alzheimer's drug repurposing

Following two decades of more than 400 clinical trials centered on the "one drug, one target, one disease" paradigm, there is still no effective disease-modifying therapy for Alzheimer's disease (AD). The inherent complexity of AD may challenge this reductionist strategy. Recent observations and advances in network medicine further indicate that AD likely shares common underlying mechanisms and intermediate pathophenotypes, or endophenotypes, with other diseases. In this review, we consider AD pathobiology, disease comorbidity, pleiotropy, and therapeutic development, and construct relevant endophenotype networks to guide future therapeutic development. Specifically, we discuss six main endophenotype hypotheses in AD: amyloidosis, tauopathy, neuroinflammation, mitochondrial dysfunction, vascular dysfunction, and lysosomal dysfunction. We further consider how this endophenotype network framework can provide advances in computational and experimental strategies for drug-repurposing and identification of new candidate therapeutic strategies for patients suffering from or at risk for AD. We highlight new opportunities for endophenotype-informed, drug discovery in AD, by exploiting multi-omics data. Integration of genomics, transcriptomics, radiomics, pharmacogenomics, and interactomics (protein-protein interactions) are essential for successful drug discovery. We describe experimental technologies for AD drug discovery including human induced pluripotent stem cells, transgenic mouse/rat models, and population-based retrospective case-control studies that may be integrated with multi-omics in a network medicine methodology. In summary, endophenotype-based network medicine methodologies will promote AD therapeutic development that will optimize the usefulness of available data and support deep phenotyping of the patient heterogeneity for personalized medicine in AD.

The Effect of Obstructive Sleep Apnea on Absolute Risk of Central Serous Chorioretinopathy

PURPOSE

To determine the incidence of central serous chorioretinopathy (CSC) stratified by age, sex, and diagnosis with obstructive sleep apnea (OSA), and to determine whether some patients with newly diagnosed CSC may be candidates for OSA evaluation.

DESIGN

Retrospective cohort study.

METHODS

We used the IBM MarketScan database to select 59,016,145 commercially insured patients in the United States between 2007 and 2016. We identified patients' first diagnosis with CSC, and defined patients as having OSA if they had a diagnosis following a sleep study. We specified Cox proportional hazard models with interactions between age, sex, and OSA status to determine patients' risk of developing CSC. We estimated the positive predictive value (PPV) that a new diagnosis of CSC would have in predicting a subsequent diagnosis of OSA.

RESULTS

Risk of CSC increased with age in years (hazard ratio [HR] = 1.030, P < .001) and OSA diagnosis (HR = 1.081, P < .033), and was lower in women (HR = 0.284, P < .001). We estimated the annual incidence of CSC was 9.6 and 23.4 per 100,000 women and men, respectively. Incidence was higher in women and men with OSA (17.2 and 40.8 per 100,000). The PPV of CSC diagnosis as a predictor of OSA was highest in the fifth decade of life.

CONCLUSION

The incidence of CSC in our patient sample is higher than previously reported. Risk of CSC is higher in men than in women, and OSA increases risk of CSC in both men and women. Some patients, particularly older male patients, may be good candidates for OSA evaluation following a CSC diagnosis.

Stem/progenitor cell-based transplantation for retinal degeneration: a review of clinical trials

Retinal degeneration (RD) is one of the dominant causes of irreversible vision impairment and blindness worldwide. However, the current effective therapeutics for RD in the ophthalmologic clinic are unclear and controversial. In recent years, extensively investigated stem/progenitor cells-including retinal progenitor cells (RPCs), embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs) and mesenchymal stromal cells (MSCs)-with proliferation and multidirectional differentiation potential have presented opportunities to revolutionise the ultimate clinical management of RD. Herein, we provide a comprehensive overview on the progression of clinical trials for RD treatment using four types of stem/progenitor cell-based transplantation to replace degenerative retinal cells and/or to supplement trophic factors from the aspects of safety, effectiveness and their respective advantages and disadvantages. In addition, we also discuss the emerging role of stem cells in the secretion of multifunctional nanoscale exosomes by which stem cells could be further exploited as a potential RD therapy. This review will facilitate the understanding of scientists and clinicians of the enormous promise of stem/progenitor cell-based transplantation for RD treatment, and provide incentive for superior employment of such strategies that may be suitable for treatment of other diseases, such as stroke and ischaemia-reperfusion injury.

Atlas of Human Retinal Pigment Epithelium Organelles Significant for Clinical Imaging

Purpose

To quantify organelles impacting imaging in the cell body and intact apical processes of human retinal pigment epithelium (RPE), including melanosomes, lipofuscin-melanolipofuscin (LM), mitochondria, and nuclei.

Methods

A normal perifovea of a 21-year-old white male was preserved after rapid organ recovery. An aligned image stack was generated using serial block-face scanning electron microscopy and was annotated by expert readers (TrakEM, ImageJ). Acquired measures included cell body and nuclear volume (n = 17); organelle count in apical processes (n = 17) and cell bodies (n = 8); distance of cell body organelles along a normalized apical-basal axis (n = 8); and dimensions of organelle-bounding boxes in apical processes in selected subsamples of cell bodies and apical processes.

Results

In 2661 sections through 17 cells, apical processes contained 65 ± 24 melanosomes in mononucleate (n = 15) and 131 ± 28 in binucleate cells (n = 2). Cell bodies contained 681 ± 153 LM and 734 ± 170 mitochondria. LM was excluded from the basal quartile, and mitochondria from the apical quartile. Lengths of melanosomes, LM, and mitochondria, respectively were 2305 ± 528, 1320 ± 574, and 1195 ± 294 nm. The ratio of cell body to nucleus volume was 4.6 ± 0.4. LM and mitochondria covered 75% and 63%, respectively, of the retinal imaging plane.

Conclusions

Among RPE signal sources for optical coherence tomography, LM and mitochondria are the most numerous reflective cell body organelles. These and our published data show that most melanosomes are in apical processes. Overlapping LM and previously mitochondria cushions may support multiple reflective bands in cell bodies. This atlas of subcellular reflectivity sources can inform development of advanced optical coherence tomography technologies.

A G-Protein Coupled Receptor and Macular Degeneration

Age-related macular degeneration (AMD) is a leading cause of irreversible blindness in the world. The risk of AMD increases with age and is most common among the white population. Here, we discuss the convergence of factors related to race, pigmentation, and susceptibility to AMD, where the primary defect occurs in retinal support cells, the retinal pigment epithelium (RPE). We explore whether the observed racial bias in AMD incidence is related to innate differences in the basal level of pigmentation between races, and whether the pigmentation pathway activity in the RPE might protect from retinal degeneration. More specifically, we explore whether the downstream signaling activity of GPR143, a G-protein coupled receptor in the pigmentation pathway, might underly the racial bias of AMD and be a target to prevent the disease. Lastly, we summarize the past findings of a large retrospective study that investigated the relationship between the stimulation of GPR143 with L-DOPA, the pigmentation pathway, and AMD, to potentially help develop new ways to prevent or treat AMD. The reader of this review will come to understand the racial bias of AMD, which is related to the function of the RPE.

Electronic Health Records for Drug Repurposing: Current Status, Challenges, and Future Directions

It is well recognized that the global pharmaceutical industry now faces challenges such as high costs and low productivity when developing new drugs (e.g., it is estimated that the average cost for developing a new drug ranges from US $2 billion to $3 billion with the total time to bring it to the market being about 13–15 years).1 Therefore, drug repurposing (also called drug repositioning/reprofiling), which finds new indications for existing drugs, has received great attention in the past decade. Drug repurposing can reduce drug development time, while improving success rates because the toxicity profiles of existing drugs are already known. Studies have shown that new applications for repurposed drugs have nearly a 30% success rate for US Food and Drug Administration (FDA) approval, whereas traditional new drug applications have < 10% approval rate.

State-of-the art pharmacotherapy for non-neovascular age-related macular degeneration

INTRODUCTION

Age-related macular degeneration (AMD) is the most common cause of blindness among the elderly in the industrialized world. While effective treatment is available for neovascular AMD, no therapy is successful for the non-neovascular form. Herein, the authors report the current knowledge on non-neovascular AMD pathogenesis and the promising research on treatments.

AREAS COVERED

In the present review, the authors summarize the most recent advances in the treatment of non-neovascular AMD and provide an update on current treatment strategies. Evidence available from preclinical and clinical studies and from a selective literature search is reported.

EXPERT OPINION

When investigating AMD, numerous pathological cascades and alterations of physiological processes have been investigated. It is well-known that AMD is a multifactorial disease, with environmental causes and genetics playing a role. Perturbations in multiple pathogenic pathways have been identified and this led to the development of several molecules directed at specific therapeutic targets. However, despite the huge research effort, the only proven approach so far is oral antioxidant supplementation. We believe that, in addition to successful advancement of promising drugs, further research should be directed at tailoring therapy to specific patient groups, eventually employing a combinational therapy strategy.

Risk factors for progression of age-related macular degeneration

Purpose

Age‐related macular degeneration (AMD) is a degenerative disease of the macula, often leading to progressive vision loss. The rate of disease progression can vary among individuals and has been associated with multiple risk factors. In this review, we provide an overview of the current literature investigating phenotypic, demographic, environmental, genetic, and molecular risk factors, and propose the most consistently identified risk factors for disease progression in AMD based on these studies. Finally, we describe the potential use of these risk factors for personalised healthcare.

Recent findings

While phenotypic risk factors such as drusen and pigment abnormalities become more important to predict disease progression during the course of the disease, demographic, environmental, genetic and molecular risk factors are more valuable at earlier disease stages. Demographic and environmental risk factors such as age and smoking are consistently reported to be related to disease progression, while other factors such as sex, body mass index (BMI) and education are less often associated. Of all known AMD variants, variants that are most consistently reported with disease progression are rs10922109 and rs570618 in CFH, rs116503776 in C2/CFB/SKIV2L, rs3750846 in ARMS2/HTRA1 and rs2230199 in C3. However, it seems likely that other AMD variants also contribute to disease progression but to a lesser extent. Rare variants have probably a large effect on disease progression in highly affected families. Furthermore, current prediction models do not include molecular risk factors, while these factors can be measured accurately in the blood. Possible promising molecular risk factors are High‐Density Lipoprotein Cholesterol (HDL‐C), Docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), zeaxanthin and lutein.

Summary

Phenotypic, demographic, environmental, genetic and molecular risk factors can be combined in prediction models to predict disease progression, but the selection of the proper risk factors for personalised risk prediction will differ among individuals and is dependent on their current disease stage. Future prediction models should include a wider set of genetic variants to determine the genetic risk more accurately, and rare variants should be taken into account in highly affected families. In addition, adding molecular factors in prediction models may lead to preventive strategies and personalised advice.

Effectiveness and safety of topical levodopa in a chick model of myopia

Animal models have demonstrated a link between dysregulation of the retinal dopamine system and the excessive ocular growth associated with the development of myopia. Here we show that intravitreal or topical application of levodopa, which is widely used in the treatment of neurological disorders involving dysregulation of the dopaminergic system, inhibits the development of experimental myopia in chickens. Levodopa slows ocular growth in a dose dependent manner in chicks with a similar potency to atropine, a common inhibitor of ocular growth in humans. Topical levodopa remains effective over chronic treatment periods, with its effectiveness enhanced by coadministration with carbidopa to prevent its premature metabolism. No changes in normal ocular development (biometry and refraction), retinal health (histology), or intraocular pressure were observed in response to chronic treatment (4 weeks). With a focus on possible clinical use in humans, translation of these avian safety findings to a mammalian model (mouse) illustrate that chronic levodopa treatment (9 months) does not induce any observable changes in visual function (electroretinogram recordings), ocular development, and retinal health, suggesting that levodopa may have potential as a therapeutic intervention for human myopia.

Systematic Evaluation of Levodopa Effect on Visual Improvement in Amblyopia: A Meta-analysis

PURPOSE

This study aims to evaluate the effectiveness of levodopa as a therapeutic drug in the treatment of children and adults with amblyopia.

METHODS

We performed a systematic review and meta-analysis with randomized controlled trials of levodopa and placebo in the treatment of amblyopia. All data were identified and extracted from the PubMed, EMBASE, Cochrane libraries, and the Chinese knowledge resource integration database.

RESULTS

After screening the literature and evaluating the quality, 11 studies met the criteria from 308 studies. The mean difference of LogMAR visual acuity between levodopa and the placebo group was -0.1031 (95% confidence interval, -0.11 to -0.09; P < 0.0001). The improvement of visual acuities of the subgroup of younger patients with amblyopia was significantly higher than that of the placebo group (P < 0.0001). Increasing the dosage of levodopa and prolonging the treatment can significantly improve the curative effect.

CONCLUSIONS

Levodopa is effective in the treatment of amblyopia by prolonging the treatment, especially for young patients.

RWE Framework: An Interactive Visual Tool to Support a Real-World Evidence Study Design

OBJECTIVES

Real-world evidence (RWE) is essential for the development of pharmaceutical and medical technologies and informs treatment-related decisions by regulatory agencies, payers, healthcare providers, and patients. Given that planning RWE studies present diverse challenges, we developed the RWE Framework, a concise, visual, interactive tool designed to align multidisciplinary stakeholders toward common goals and encourage a methodical approach to RWE study planning.

METHODS

A search of published literature and internet-based resources was performed to identify guidance on RWE study planning with decision and/or visual aids. A conceptual framework for a study design tool was developed based on best practices for RWE studies, enhanced with an infographic design, and refined by multidisciplinary input from RWE researchers.

RESULTS

The searches confirmed an unmet need for a concise tool to support a broad range of RWE study designs: only two sources with decision/visual aids were identified. The novel RWE Framework comprises sequential decision steps with instructions to guide users through consideration of research objectives, product approval status, study setting, outcomes of interest, data availability in routine practice, need for primary data collection and/or randomization, study type and methodology, and applicable regulatory standards. Pilot testing using case studies of pharmaceutical assets demonstrated the utility of RWE Framework and applicability for use in team environments.

CONCLUSIONS

The RWE Framework is a novel, concise, visual, and interactive tool to inform RWE study planning. It addresses a broad range of real-world study types and research objectives and was found to enhance RWE decision-making by multidisciplinary teams. Further validation is warranted.

Data Driven Approach for Eye Disease Classification with Machine Learning

Medical health systems have been concentrating on artificial intelligence techniques for speedy diagnosis. However, the recording of health data in a standard form still requires attention so that machine learning can be more accurate and reliable by considering multiple features. The aim of this study is to develop a general framework for recording diagnostic data in an international standard format to facilitate prediction of disease diagnosis based on symptoms using machine learning algorithms. Efforts were made to ensure error-free data entry by developing a user-friendly interface. Furthermore, multiple machine learning algorithms including Decision Tree, Random Forest, Naive Bayes and Neural Network algorithms were used to analyze patient data based on multiple features, including age, illness history and clinical observations. This data was formatted according to structured hierarchies designed by medical experts, whereas diagnosis was made as per the ICD-10 coding developed by the American Academy of Ophthalmology. Furthermore, the system is designed to evolve through self-learning by adding new classifications for both diagnosis and symptoms. The classification results from tree-based methods demonstrated that the proposed framework performs satisfactorily, given a sufficient amount of data. Owing to a structured data arrangement, the random forest and decision tree algorithms’ prediction rate is more than 90% as compared to more complex methods such as neural networks and the naïve Bayes algorithm.

Genetically-guided algorithm development and sample size optimization for age-related macular degeneration cases and controls in electronic health records from the VA Million Veteran Program

Electronic health records (EHRs) linked to extensive biorepositories and supplemented with lifestyle, behavioral, and environmental exposure data, have enormous potential to contribute to genomic discovery, a necessary step in the pathway towards translational or precision medicine. A major bottleneck in incorporating EHRs into genomic studies is the extraction of research-grade variables for analysis, particularly when gold-standard measurements are not available or accessible. Here we develop algorithms for age-related macular degeneration (AMD), a common cause of blindness among the elderly, and controls free of AMD. These computable phenotypes were developed using billing codes (ICD-9-CM and ICD-10-CM) and Current Procedural Terminology (CPT) codes and evaluated in two study sites of the Veterans Affairs Million Veteran Program: Louis Stokes Cleveland VA Medical Center and the Providence VA Medical Center. After establishing a high overall positive and negative predictive values (93% and 95%, respectively) through manual chart review, the candidate algorithm was deployed in the full VA MVP dataset of >500,000 participants. The algorithm was then optimized in a data cube using a variety of approaches including adjusting inclusion age thresholds by examining previously-reported genetic associations for CFH (rs10801555, a proxy for rs1061170) and ARMS2 (rs10490924). The algorithm with the smallest p-values for the known genetic associations was selected for downstream and on-going AMD genomic discovery efforts. This two-phase approach to developing research-grade case/control variables for AMD genomic studies capitalizes on established genetic associations resulting in high precision and optimized sample sizes, an approach that can be applied to other large-scale biobanks linked to EHRs for precision medicine research.

Treatments for dry age-related macular degeneration and Stargardt disease: a systematic review

BACKGROUND

Age-related macular degeneration (AMD) is the leading cause of visual loss in older people. Advanced AMD takes two forms, neovascular (wet) and atrophic (dry). Stargardt disease (STGD) is the commonest form of inherited macular dystrophy.

OBJECTIVE

To carry out a systematic review of treatments for dry AMD and STGD, and to identify emerging treatments where future NIHR research might be commissioned.

DESIGN

Systematic review.

METHODS

We searched MEDLINE, EMBASE, Web of Science and The Cochrane Library from 2005 to 13 July 2017 for reviews, journal articles and meeting abstracts. We looked for studies of interventions that aim to preserve or restore vision in people with dry AMD or STGD. The most important outcomes are those that matter to patients: visual acuity (VA), contrast sensitivity, reading speed, ability to drive, adverse effects of treatment, quality of life, progression of disease and patient preference. However, visual loss is a late event and intermediate predictors of future decline were accepted if there was good evidence that they are strong predictors of subsequent visual outcomes. These include changes detectable by investigation, but not necessarily noticed by people with AMD or STGD. ClinicalTrials.gov, the World Health Organization search portal and the UK Clinical Trials gateway were searched for ongoing and recently completed clinical trials.

RESULTS

The titles and abstracts of 7948 articles were screened for inclusion. The full text of 398 articles were obtained for further screening and checking of references and 112 articles were included in the final report. Overall, there were disappointingly few good-quality studies (including of sufficient size and duration) reporting useful outcomes, particularly in STGD. However we did identify a number of promising research topics, including drug treatments, stem cells, new forms of laser treatment, and implantable intraocular lens telescopes. In many cases, research is already under way, funded by industry or governments.

LIMITATIONS

In AMD, the main limitation came from the poor quality of much of the evidence. Many studies used VA as their main outcome despite not having sufficient duration to observe changes. The evidence on treatments for STGD is sparse. Most studies tested interventions with no comparison group, were far too short term, and the quality of some studies was poor.

FUTURE WORK

We think that the topics on which the Health Technology Assessment (HTA) and Efficacy Mechanism and Evaluation (EME) programmes might consider commissioning primary research are in STGD, a HTA trial of fenretinide (ReVision Therapeutics, San Diego, CA, USA), a visual cycle inhibitor, and EME research into the value of lutein and zeaxanthin supplements, using short-term measures of retinal function. In AMD, we suggest trials of fenretinide and of a potent statin. There is epidemiological evidence from the USA that the drug, levodopa, used for treating Parkinson's disease, may reduce the incidence of AMD. We suggest that similar research should be carried out using the large general practice databases in the UK. Ideally, future research should be at earlier stages in both diseases, before vision is impaired, using sensitive measures of macular function. This may require early detection of AMD by screening.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42016038708.

FUNDING

The National Institute for Health Research HTA programme.

The identification of small molecules that stimulate retinal pigment epithelial cells: potential novel therapeutic options for treating retinopathies

INTRODUCTION

Combinatory strategies using pharmacology and stem cell therapy have emerged due to their potential in the treatment of retinal pigment epithelium (RPE) cell related diseases, and a variety of different stem cell sources have been evaluated both in animal models and in humans. RPE cells derived from human embryonic stem cells (hESCs) and human induced pluripotent cells (hiPSCs) are already in clinical trials, holding great promise for the treatment of age-related macular disease (AMD) and hereditary RPE-related retinal dystrophies. Highly efficient protocol for RPE generations have been developed, but they are still time-consuming and laborious. Areas covered: The authors review RPE related diseases, as well as the known functions of RPE cells in retinal homeostasis. The authors also discuss small molecules that target RPE in vivo as well as in vitro to aid RPE differentiation from pluripotent stem cells clinically. The authors base this review on literature searches performed through PubMed. Expert opinion: Using high-throughput systems, technology will provide the possibility of identifying and optimizing molecules/drugs that could lead to faster and simpler protocols for RPE differentiation. This could be crucial in moving forward to create safer and more efficient RPE-based personalized therapies.